A61M5/31576—Constructional features or modes of drive mechanisms for piston rods

A61M5/31578—Constructional features or modes of drive mechanisms for piston rods based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod

A61M5/3158—Constructional features or modes of drive mechanisms for piston rods based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod performed by axially moving actuator operated by user, e.g. an injection button

B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents

B65D81/32—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging two or more different materials which must be maintained separate prior to use in admixture

B65D81/325—Containers having parallel or coaxial compartments, provided with a piston or a movable bottom for discharging contents

G01F11/00—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it

G01F11/02—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement

G01F11/021—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement of the piston type

G01F11/025—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement of the piston type with manually operated pistons

G01F11/00—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it

G01F11/02—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement

G01F11/021—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement of the piston type

G01F11/025—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement of the piston type with manually operated pistons

G01F11/027—Apparatus requiring external operation and adapted at each repeated and identical operation to measure and separate a predetermined volume of fluid or fluent solid material from a supply or container without regard to weight and to deliver it with measuring chambers which expand or contract during measurement of the piston type with manually operated pistons of the syringe type

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/178—Syringes

A61M5/24—Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or carpules, e.g. automatic

A61M2005/2403—Ampoule inserted into the ampoule holder

A61M2005/2411—Ampoule inserted into the ampoule holder from the front

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/31593—Multi-dose, i.e. individually set dose repeatedly administered from the same medicament reservoir

A—HUMAN NECESSITIES

A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE

A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR

A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests

A61M5/50—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests having means for preventing re-use, or for indicating if defective, used, tampered with or unsterile

A61M5/5013—Means for blocking the piston or the fluid passageway to prevent illegal refilling of a syringe

A61M5/502—Means for blocking the piston or the fluid passageway to prevent illegal refilling of a syringe for blocking the piston

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE

Y02W30/807—Packaging containers especially suited for or with means facilitating reusability

Abstract

A pharmaceutical dispenser includes a housing (4), containing two pharmaceutical cartridges (32, 34), slidably mounted to a sliding body (100). A replaceable needle manifold assembly (10) is mounted to the housing and fluidly couples the cartridges with a hypodermic needle at a common exit. The sliding body is part of a reciprocating drive assembly used to drive a pair of drive stems (88) against the pistons (96, 98) of the cartridges, thus forcing predetermined amounts of the pharmaceuticals out the needle. The movement of the sliding body between retracted and post-injection positions remains constant. However, the amounts and proportions of the pharmaceuticals injected during the delivery stroke is chosen by the user using stroke adjusters (182) carried by the sliding body. A bistable status flag (186) is mounted to the sliding body to indicate when the sliding body is in the post-injection and retracted positions. If a dose selected is more than is available, the status flag is not tripped.

Description

BACKGROUND OF THE INVENTION

Frequently a physician will prescribe two or more
medications to be taken by a patient either simultaneously or
as close to simultaneously as practical. This is often the
case in prescribing insulin. Two basic types of insulin are
most frequently prescribed: regular, a fast-acting variety, and
NPH, an intermediate-acting variety. Additionally, a longer-acting
type of insulin called ultralente is also available.
These types of insulin differ in their onset and duration of
action. Regular insulin typically has the quickest onset and
the briefest duration of action. The onset and duration of
insulin may be modified by chemical manipulations which include
precipitation with protamine or suspension with isophane or
zinc. Injectable insulin is derived from pigs and cattle, and
a semi-synthetic genetically-engineered human form is available
commercially.

Regardless of the final chemical composition or
origin of the insulin prescribed, the physician frequently
advises the patient to mix two or more types of insulin and to
inject them at least once a day. Some patients respond best to
a schedule of two or three daily doses, usually in conjunction
with meals. Frequently trial-and-error type of evaluation is
practiced to arrive at the correct dosing and combination for
the individual patient. However, after this initial adjustment
period, the patient may be maintained on the same dose and
proportion of insulins for many weeks or months assuming that
the patient's diet, activity, and state of health remain
reasonably constant or predictable. An example of a typical
mixture and ratio of insulins is 70% NPH and 30% regular
insulin injected just prior to a meal.

The implications of insulin therapy for the patient
generally include the need for two separate sets of insulin
injection syringes and needles. This is because the patient
will usually draw a predetermined amount of insulin from each
of two vials. A sophisticated patient may be able to use a
single syringe and simply draw up the correct amount from each
separate insulin vial. However, he may prefer to use two
separate needles because of the danger of mixing two types of
insulin by using a needle "contaminated" with one type of
insulin and accidentally getting some of the first insulin into
the second vial from which he draws the second insulin. If the
patient is not sophisticated or not adept at drawing up insulin
from a vial into a syringe, he would need two needles and two
syringes. He may find that he has drawn up too much insulin
and then he wishes to return the excess to the vial. If he is
using a single syringe, he cannot return the excess to the vial
if he is presently attempting to draw insulin from the second
vial. The problem of getting the correct amount and proportion
of each type of insulin prescribed is an everyday difficulty
which the diabetic patient may face two or three times a day.

Besides insulin, other medications may be
advantageously prescribed as a simultaneous or near-simultaneous
dose. For example, pain medications of the opiate
family are frequently prescribed together with antiemetics.
The antiemetic drugs are often useful as potentiators of
narcotic painkillers and additionally they may ameliorate some
of the side effects of narcotics such as nausea and vomiting.
For example, a patient who has chronic pain, such as that
associated with metastatic cancer, may take 50 milligrams of
meperidine (a narcotic) and 25 milligrams of hydroxyzine (an
antiemetic) intramuscularly several times a day. Patients
having chronic pain are often managed in a long-term care
facility such as a nursing home. Alternatively, an outpatient
setting is sometimes feasible if the patient or his family can
administer medications.

Unfortunately, many patients requiring either chronic
pain medication or insulin find that they have some difficulty
with their eyesight. This may be especially true of the older
age group. Additionally, diabetics who require insulin
replacement frequently suffer deterioration of vision as a
consequence of the diabetic process. Thus, people who are
often in greatest need of multiple injected medications of a
defined dose and proportion may ironically find their drug
regimen most difficult to regulate precisely. Another problem
arises in the context of long-term care facilities such as
nursing homes. Frequently the nurse who administers injectable
drugs is pressed for time on medication rounds. The time
pressure is compounded if the care facility is constrained by
budgetary or other non-medical concerns. A device which
permits accurate dosing and proportion of two or more
medications and which allows for repetitive dosing in the same
proportions could be useful to a variety of patients in a
variety of circumstances.

From WO 92/10425 a fluid dispenser is known which is designed as a
variable proportion dispenser for simultanously administering two medications
comprising two variable volume containers, including exits and
movable elements, two corresponding drive stems and a drive assembly,
including two drivers and two stroke adjusters.

SUMMARY OF THE INVENTION

The present invention is directed to a reusable
pharmaceutical dispenser which provides the user with a
distinct visual indication when the assembly is at the very end
of its delivery (or injection) stroke and at the very end of
its retraction (post-return) stroke. The invention is
especially useful for dispensing different types of insulin in
amounts and proportions selected by the user. Once the
combined dosage is selected, both in amount and proportion, the
same dosage will be automatically dispensed during each
actuation cycle of the dispenser. The invention, as an insulin
delivery system, permits the total amount of the insulin
injected and the proportion of, for example, NPH and regular
human insulin to be user selected. The dispenser is designed
to permit the user to easily and quickly replace spent
pharmaceuticals containing cartridges and the used manifold
assembly to which the used needle is mounted.

The pharmaceutical dispenser includes a housing which
contains two pharmaceutical cartridges. The housing is
slidably mounted to a sliding body, preferably using a guide
sleeve which acts as a an extension of the housing and slidably
mounts over the sliding body. A manifold assembly is mounted
to the housing and fluidly couples the interiors of the
cartridges with a common exit, preferably adapted to accept a
hypodermic needle for giving injections. The manifold assembly
is easily removable from the housing to aid removal and
replacement of spent cartridges, the used manifold assembly and
the used needle without the need for special tools.

The sliding body is part of a reciprocating drive
assembly used to drive a pair of drive stems against the
pistons of the cartridges. Doing so forces predetermined
amounts of the pharmaceuticals within the cartridges from the
cartridges, to the manifold and out the common exit, typically
through a hollow hypodermic needle. The sliding body can move
in a proximal direction to a first, retracted (post-return)
position and in a distal direction to a second, post-delivery
or post-injection position, and back again, during each cycle
of the dispenser.

The distance that the slider body moves relative to
the housing between the first and second positions remains
constant. However, the amount of liquid pharmaceutical
injected during the delivery stroke is chosen by the user.
This is accomplished using dose adjusters carried by the
sliding body. The dose adjusters preferably use a threaded
connection to adjust the amount of pharmaceutical to be
injected from each cartridge. The position or setting of the
dose adjuster determines how far a one-way drive device (or
ratchet assembly) drives the drive stem during each delivery
stroke.

The one-way drive device includes an anti-backup
ratchet plate, mounted to the housing, which prevents the drive
stems from moving in the proximal direction during the return
stroke of the sliding body. The one-way drive device also
includes a pair of ratchet disks, associated with the sliding
body, which drive the drive stems towards the cartridge pistons
during the delivery stroke of the sliding body.

The setting of each dose adjuster is indicated using
a dose indicator which changes its axial position along the
sliding body according to the dosage set. This is preferably
achieved using a relatively large-pitched thread along one of
the dose adjuster elements so that the movement of the dose
indicator is an amplified version of the dose adjuster
movement.

The invention includes, according to a further embodiment, a status
window flag, in the preferred embodiment pivotably mounted to the sliding
body, to provide a visual indication when the sliding
body has been moved to the post-injection position and to the
retracted position at the very end of the delivery and return
strokes, respectively. This is achieved in the preferred
embodiment using a status window flag pivotally mounted within
a recess formed in the sliding body. The status window flag
can move between two extreme positions. In one position, the
status window flag directly underlies a status window formed in
the guide sleeve. In the other position, a status window flag
is not visible through the status window; rather, one sees a
panel, typically with an informing indicator, underlying the
status window.

The status window flag is preferably moved between
the two extreme positions using an S-shaped, over-center spring
having one end positioned adjacent to the pivot of the flag and
the other one pressing against the sliding body. The over-center
spring is formed and positioned such that the flag has
two stable positions corresponding to the post-injection and
retracted positions of the sliding body. The flag is moved
between the two positions by the engagement of trip pins
extending inwardly from the guide sleeve. The trip pins are
positioned to engage and trip the over-center spring at the
very end of travel of the sliding body. In this way, the user
receives a visual and audible indication of when the sliding
body is at the end of travel during each stroke to ensure that
a complete injection is given. To avoid any ambiguity, the
status indicator shifts suddenly and fully at the extreme
positions of the stroke, so the user is never presented with a
potentially confusing partly-visible retraction indication.

The dosage adjustments in the preferred embodiment
are made when the sliding body is in the post-injection
position. To prevent inadvertent movement of the sliding body
from the post-injection position, a post-injection latch is
carried by the guide sleeve. The post-injection latch
automatically engages an appropriately positioned recess in the
sliding body when the sliding body is in the post-injection
position. Only by depressing the post-injection latch can the
user move the sliding body out of the post-injection position
to the retracted position.

The invention also provides, according to a further embodiment, an
indication to the user whether there is sufficient pharmaceutical left in the
cartridge for the desired set dose. In the preferred
embodiment this is achieved by forming a shallow groove along a
portion of a length of each drive stem. Ratchet disk housings,
which are coupled through the dose adjusters to the slider
housing, have inwardly projecting elements which ride in the
shallow grooves. As the stems advance, the end of the shallow
grooves will limit the ratchet collar and therefore the slider
housing's rearward (i.e., proximal) movement. If the available
remaining pharmaceutical is less than the dose selected, the
slider housing will not be able to be moved to the full
retracted position and will not trip the status flag to display
an indicium indicating the dispenser is configured for an
injection. The user can rotate the dose knob reducing the dose
to permit the status flag to trip. The user can then check the
dose indicator along the side of the sliding body to determine
what dose of medication is available for that last injection.

When it is desired to replace a spent cartridge, the
fingers of the ratchet disks and the anti-backup ratchet plate,
which normally engage the drive stems, are dilated through the
use of release forks positioned coaxially with the drive stems.
The release forks can move independent of the drive stems.
During the normal axial movement of the drive stems the release
forks do not release the ratchet disks from the stems.
However, when the sliding body is in the retracted position,
the dose adjusters can be threaded into the sliding body to
drive the release forks against the ratchet disks to dilate the
fingers of the ratchet disks and thus release the ratchet disks
from the drive stems. The axial movement of the release forks
also forces the ratchet disk housing, which has a pair of
ratchet plate release prongs, against the ratchet plate to
dilate the fingers of the ratchet plate thus releasing the
drive stem from the ratchet plate as well. The unintentional
threading of the dose knobs into the slider housing is
prevented by requirement to shift the release switch before the
dose knob thread can engage the slider housing threads. The
needle manifold is then separated from the cartridge housing to
expose the cartridges. The cartridges are then removed to
expose the drive stems. This allows the drive stems to be
forced in the proximal direction back towards their initial or
as-shipped positions to accommodate full replacement
cartridges.

Some users may suffer from a certain degree of
confusion; the simultaneous visual display of two (or more)
dose indicators when setting the dose for each component could
create problems for these users. With a two-component
dispenser, it is preferred that the dose indicator for each
component be visually perceptible from opposite sides of the
dispenser. Thus, when a user sets the dose, by rotating the
dose adjustor, only one dose indicator is visible. This helps
to ensure that the user does not become confused as to the dose
selected.

In the present embodiment the axial position of the
drive coupling prior to the return stroke determines the dose.
The visual indication of this axial movement can be magnified
by the dose indicator. For example, assume that an axial
movement of three millimeters by the drive stem corresponds to
one unit of medication. With the present invention, the dose
indicator can be driven in much a way that the dose indicator
moves, for example, six millimeters for every three millimeters
the drive stem is to move. This permits the units of
medication markings, typically carried by the sliding body, to
be spaced twice as far apart as would otherwise be possible
thus greatly enhancing ease of use and accuracy.

One of the primary advantages of the invention is
that it permits the user to adjust both the quantity and
proportion of the two components to be delivered by the
dispenser. The setting stays the same for multiple duplicate
doses without the need for any additional adjustment although
additional adjustment is allowed.

Other features and advantages of the invention will
appear from the following description in which the preferred
embodiments have been set forth in detail in conjunction with
the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an overall isometric view of a
pharmaceutical dispenser made according to the invention with
the sliding body in the post-injection position;

Fig. 2 is an exploded isometric view of the dispenser
of Fig. 1;

Fig. 3 is a cross-sectional view of the dispenser of
Fig. 1;

Fig. 4 is an enlarged view of the distal portion of
the dispenser of Fig. 3 showing the manifold assembly;

Fig. 5 is an enlarged view of the central portion of
the dispenser of Fig. 3 showing the release forks and the
release prongs opposite the ratchet disks and the anti-backup
ratchet plate in the non-release status;

Fig. 5A is a cross-sectional view of a drive stem of
Fig. 2;

Fig. 5B is a perspective view of a stem usable in
connection with a 3.0 ml cartridge;

Fig. 5D is an isometric view of a ratchet disk of
Fig. 2;

Fig. 6 is an enlarged view of the proximal portion of
the dispenser of Fig. 3 illustrating the abutment of the
external thread on the knob core against the proximal end of
the sliding body;

Fig. 8 is an enlarged view of a knob core of Fig. 2
showing the external release thread;

Fig. 9 is a simplified enlarged rear view of the
guide sleeve of Fig. 1 showing the post-injection latch and
limit pin;

Fig. 9A is a cross-sectional view taken along line
9A-9A of Fig. 9 in the post-injection configuration with the
post-injection latch engaging a recess in the sliding body and
the limit pin extending from the sliding body into a retract
limit slot formed in the guide sleeve;

Fig. 9B is similar to Fig. 9A but shows the pivotal
movement of the post-injection latch to disengage from the
recess in the sliding body to permit the sliding body to be
moved in a proximal direction until the limit pin contacts the
distal end of the retract limit slot, typically a distance of 7
millimeters;

Fig. 10 is an enlarged simplified view of the slider
body with the status window flag as it would be after the
sliding body has moved distally to the post-injection position.
At the end of the delivery stroke, the flag and over-center
spring are shown in dashed lines to indicate their positions
after the sliding body has been moved to the retracted position
at the end of the return stroke; and

Fig. 11 is an exploded view partly cut-away of an
alternative embodiment for the engagement of the knob core with
the screw, using a slip clutch mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Pharmaceutical dispenser 2 is shown in Fig. 1 to
include a housing 4; housing 4 includes a cartridge housing 6
and a guide sleeve 8 secured thereto. Guide sleeve 8 acts as
an extension of cartridge housing 6. Referring now also to
Figs. 2-4, a manifold assembly 10, mounted to the distal end 12
of cartridge housing 6, includes a manifold body 14, a manifold
housing 16 and an elastomeric diaphragm 18 mounted between the
two. The diaphragm 18 includes an upwardly extending tube 19,
defining a central bore 46. Housing 16 includes a threaded tip
20 against which a needle guiding funnel 22 is mounted. Funnel
22 has a needle-pierceable septum 24 positioned against the
funnel and held in place by a septum cap 26, which is
threadably secured to threaded tip 20. Needle funnel 22 acts
as a guide for the inner end of a double ended hypodermic
needle, not shown, which is mounted to septum cap 26 when it is
desired to give an injection. The funnel 22 avoids piercing
the tube 19 with the inner end of the needle, and also forms a
seal with the tube 19, since the outer diameter of the upper
end of the funnel 22 is greater than the diameter of the bore
46, causing the upper end of the tube 19 to elastically distend
and form a tight seal with the funnel 22.

Cartridge housing 6 includes a pair of cartridge
receiving bores 28, 30 sized to accept cartridges 32, 34.
Cartridge 32 is preferably a 3 ml cartridge while cartridge 34
is a 1.5 ml cartridge; however, other size cartridges or the
same size cartridge could be used as well. Cartridges 32, 34
each have a septum 36 (Fig. 4) at one end which is pierced by a
spike 38 extending from manifold body 14. Doing so permits the
contents 40, 42 of cartridges 32, 34 to flow through spikes 38
and past cup-shaped extensions 41 of diaphragm 18 between
relatively rigid manifold body 14 and elastomeric diaphragm 18.
The necessary upward deflection of diaphragm 18 is possible due
to presence of a region 44 defined between diaphragm 18 and
manifold housing 16 (Fig. 4). Contents 40, 42 then continue up
a central bore 46 formed in diaphragm 18 where the contents can
flow into the inner end of the double ended hypodermic needle
(not shown) mounted to septum cap 26. Accordingly, manifold
assembly 10 provides a central or common exit for contents 40,
42. Diaphragm 18 and particularly the cup-shaped extensions
thereof 41 act as a check-valve to prevent flow through the
spikes 38 except under circumstances in which the contents 40,
42 of the cartridges 32, 34 are sufficiently pressurized (e.g.,
with respect to the pressure at the distal ends of the spikes
38) that flow through the spikes 38 is guaranteed to be
outflow. This guards against cross-contamination of the
cartridges and waste of pharmaceuticals, e.g., by preventing
fluid exit when no needle is installed.

The natural resiliency of the diaphragm 18 aids in
reducing the amount of residual pharmaceutical, i.e., the
pharmaceutical which has exited the cartridges 32, 34, but is
not expelled from the needle. It is desired to reduce the
residual to avoid the potential for bacterial growth or other
contamination. According to one embodiment, residual is
reduced by expelling pharmaceutical even after flow of
pharmaceutical through the spikes has ceased. This is achieved
by relying on the natural resiliency of the diaphragm 18 to
cause the diaphragm to relax into its preferred position
adjacent the manifold body 14 thus expelling pharmaceutical
which may be contained between the manifold body 14 and the
diaphragm 18 through the central bore 46.

Cartridge 6 has a pair of manifold assembly release
buttons 48, 50 slidably mounted to the housing. Buttons 48, 50
have extensions 52, 54 which extend into a guide slot 56 formed
in cartridge housing 6. Extensions 52, 54 are secured to one
another within slot 56 by the engagement of a pair of pins 58
extending from extension 52 which engage complementary holes
(not shown) formed in extension 54 and secured in place through
use of an adhesive or through a friction fit. Slot 56 is sized
to permit buttons 48, 50 to move axially toward and away from
manifold assembly 10. Leading surfaces 60 of buttons 48, 50
are shaped and positioned to engage internal bevels 62 formed
on the proximal ends of a pair of latches 64 of manifold housing
16. To remove manifold housing 10, the user forces buttons 48,
50 towards manifold assembly 10, that is in the distal
direction, so that surfaces 60 engage internal bevels 62. This
deflects tabs 64 outwardly so that pegs 66, extending from
cartridge housing 6, are disengaged from holes 68 formed in
tabs 64 to permit the user to pull a manifold assembly 10 away
from cartridge housing 6. Doing so exposes cartridges 32, 34
so that they can be removed and replaced as desired.

Guide sleeve 8, also shown in Fig. 7, has a generally
open interior 70 with a ledge 72 formed near the distal end 74
of the guide sleeve. Ledge 72 has a pair of holes 76 sized to
accept screws 78 (see Fig. 2). Screws 78 pass through holes
76, through holes 80 formed in an anti-backup ratchet plate 82,
discussed below, and into threaded holes, not shown, formed in
the proximal end 83 of cartridge housing 6. Accordingly,
cartridge housing 6 and guide sleeve 8 are rigidly secured to
one another. Guide sleeve 8 includes an integrally formed post
injection latch 84 connected to guide sleeve 8 through tabs 86.
The use of latch 84 will be discussed below.

Dispenser 2 includes a pair of drive stems 88 which
have a pair of longitudinal drive grooves 90, see Fig. 5A,
formed along their entire lengths and a pair of shallow end-of-dose
grooves 92 formed along a portion of their lengths. The
distal ends 94 of drive stems 88 are forced against the pistons
96, 98 of cartridges 32, 34 through the use of a reciprocating
drive assembly.

The reciprocating drive assembly includes a sliding
body 100 to which is mounted a pair of dose adjusters 102 (see
Figs. 2, 3 and 7A). Dose adjusters 102 each include a dose
adjustment screw driver 104 which is operably connected to a
dose adjustment screw 106. A drive coupling 108 has external
threads 110 which mate with internal threads 112 on screw 106.
Screw drivers 104 each include a dose knob 114 mounted to a
knob core 116 by a screw 118 (see Figs. 2 and 6). Knob cores
116 are keyed to dose adjustment screws 106 through the use of
grooves 120 formed on knob cores 116 and inwardly extending
splines 122 formed within screws 106. This permits the user to
transfer rotary motion from dose knobs 114, through knob core
116 and to dose adjustment screws 106 while permitting the dose
adjustment screw drivers to be moved in a proximal direction
away from sliding body 100. This aids user manipulation of
dose knobs 114 as shown in Fig. 1.

Preferably, as shown in Fig. 2, the splines 122
extend only partially up the interior surface of the knob cores
116. Thus, in the normal operating position, with the knobs
114 adjacent the release switch 236 (as described more fully
below) the grooves 120 will be positioned above the splines 122
so that there will be no rotational engagement of the
screwdrivers 104 with the dose adjustment screws 106. This
avoids inadvertent dose changes when the dispenser 2 is in its
operating configuration.

When it is desired to change a dose, preferably while
the dispenser 2 is in its post-injection position, the user
pulls on one of the knobs 114 to retract the knob and attached
knob core 116 downward partially through the dose adjustment
screw 106 to the position depicted in phantom lines in Fig. 1
so as to engage the grooves 120 with the splines 122. Once one
of the knobs 114 is in this position, rotating the knob 114
will cause rotation of the knob core 116 and the engagement of
the grooves 120 with the splines 122 will also cause rotation
of the dose adjustment screws 106. By moving one of the knobs
114 outward before adjusting a dose, it is possible to position
one of the dose adjustment knobs 114 away from the other during
the dose adjustment procedure, thus making it easier for the
user to rotate one of the dose adjustment knobs without moving
the other. Following the rotation of the withdrawn knob to
achieve the desired dose adjustment, the knob is then pushed
back toward the body of the dispenser 2, adjacent the release
switch 236 and, if desired, the user may then adjust the dosage
on the other side by retracting and rotating the second knob.

Dose adjustment screws 106 are free to rotate within
bores 124, 126 of sliding body 100. Screws 106 have
circumferential grooves 128 at their proximal ends. An arcuate
T-shaped adjustment screw keeper 130 is mounted in a slot 131
in sliding body 100 and engages grooves 128 to maintain screws
106 in a fixed axial position within sliding body 100 while
permitting rotation. The rotary movement of each of screws 106
is indicated by the movement of a dose indicator 132. Each
indicator 132 has an inwardly directed follower 134 which
engages a large pitched external thread 136 formed on the
outside of screws 106. Dose indicators 132 ride within slots
138 formed in sliding body 100. In one embodiment, it is
desired to provide for clarity of the dose indication by using
a dose indicator mechanism which amplifies the movement of the
screw-drive coupling engagement 116, 110. In this embodiment,
amplification is provided by using a pitch for the threads 136
which is larger for the pitch for the internal threads 112 of
the screw 106. For example, if the internal threads 112 have a
pitch of 9,06 threads per cm (23 threads per inch), the external
threads 136 can be provided with a pitch of, for example,
1,38 threads per cm (3½ threads per inch) to provide an amplification
of about 6.5. Such amplification provides a clear visual
indication of dosage, despite
relatively small adjustment of a coupling body 110 engagement
with the screw threads 112, which is particularly useful for
users with impaired vision. Elastomeric O-rings 140 are
positioned between the proximal ends 142 of dose adjustment
screws 106 and an internal ledge 144 of sliding body 100. This
provides sufficient frictional resistance to maintain
adjustment screw driver 104 at an axial position selected by
user.

In one embodiment, it is preferred to prevent over-rotation
of the screws 106, and in particular to prevent
rotation which will drive the coupling 108 either proximally or
distally out of engagement with the threads 112. Over-driving
in one direction, e.g., proximally, can be prevented by
providing a positive stop in the last thread of the internal
threads 112. However, it is desired to assemble the dispenser
2 by a procedure which includes threading the coupling threads
110 into engagement with the screw threads 112 and thus it is
not practical in this embodiment to provide positive stops at
both ends of the threads 112. Therefore, another device can be
used to prevent over-driving the coupling 108 in a distal
direction. It is possible to rely on contact of the dose
indicator 132 with the end of one of the slots 138 as a stop to
indicate the preferred end of travel of the coupling 108 with
respect to the threads 112. However, if a user attempts to
rotate the knobs 114 after the indicators 132 reach the end of
the slots 138, by applying sufficient force, the user may drive
an indicator 132 underneath the slider housing, thus over-driving
the coupling 108 and eventually damaging the dispenser
2.

Fig. 11 depicts an alternative embodiment that can be
used to prevent over-driving the coupling 108. In the
embodiment of Fig. 11, the proximal rim of the screw 106 is
castellated to provide a plurality of detents 320. A dilating
bushing 322 has a tapered portion 324 configured to fit within
the proximal interior volume of the screw 106 and having a
plurality of exterior teeth 326 which inter-digitate with
detents 320 so that torque about axis 328 applied to the
bushing 322 will be transmitted by the teeth 326 to the screw
106 normally causing rotation thereof. The bushing 322 is held
in an inter-digitating position with the screw 106, e.g., by an
o-ring similar to the o-ring 140 depicted in Fig. 2. A knob
core 116' is provided which is similar to the knob core 116
depicted in Fig. 2 except that the flange 330 may have a
smaller axial extent than the corresponding flange of the core
116, and need not have grooves 120, and also includes external
teeth 332. The external teeth 332 of the knob core 116' are
configured to mesh with internal teeth 334 formed in the
tapered portion 324 of the bushing 322. In order to rotate the
screw 106 for dosage adjustment purposes, a knob 114 attached
to the proximal end of the knob core 116' is pulled proximally
to partially withdraw or "telescope" the knob core to a
position similar to that depicted by phantom lines in Fig. 1.
When the core 116' is withdrawn to this position, the external
teeth 332 mesh with the internal teeth 334. When the knob core
116' is rotated (e.g., by rotation of an attached knob 114)
about axis 328 this torque is transmitted by the teeth 332, 334
to create a torque about axis 328 on the bushing 322. The
bushing on the torque 322 is, in turn, transmitted by teeth 326
in detents 320 to the screw 106, normally resulting in rotation
thereof about axis 328. The tapered portion 324 includes one
or more slots 336 to permit the tapered portion 324 to dilate
outward when subjected to a sufficiently great outward force
and to return to the tapered configuration depicted in Fig. 11
by virtue of the resiliency of the tapered portion 324. When
the dosage indicator 132 riding in the external threads 136 of
the screw 106 reach the end of one of the slots 138, further
movement of the dose indicator is resisted by the end of the
slot 138 and this in turn causes resistance to continued
rotation of the screw 106. This resistance to rotation of the
screw 106 is sufficiently great that continued torque on the
knob core 116' (e.g., by continued torque on a knob 114) causes
the teeth 133 to travel up the side of the meshing teeth 334 of
the bushing 322, causing dilation of the tapered portion 324.
The tapered portion 324 has sufficient taper that it can dilate
in amount large enough to permit the external teeth 332 to ride
over the meshing teeth 334. Thus, continued attempts to rotate
a knob 116 after the indicator 132 has reached the end of the
slot 138 will not produce further rotation of the screw 106 but
will, instead, cause the slip clutch mechanism 322, 332 to
effectively disengage so that the knobs 114 will be turned
without the corresponding rotation of the screw 106. During
this operation, the user will receive a tactile vibrating or
buzzing feedback to signal the user that the end of the dose
adjustment scale has been reached. This tactile feedback is
useful particularly with vision-impaired users. In addition to
providing tactile feedback and avoiding over-driving of the
coupling 108, the embodiment of Fig. 11 is also advantageous
over the embodiment depicted in Fig. 2 because it can be more
easily molded.

The rotary motion of screws 106 imparts an axial
motion to drive couplings 108. This occurs because drive
couplings 108 are connected to ratchet disk housings 146
through the engagement of lugs 148 within axially-extending
drive slots 150 formed in generally cylindrical housings 146.
Housings 146 include radially outwardly extending drive lugs
152 which are housed within slots 154 formed at the distal end
156 of sliding body 100. Accordingly, rotary movement of screw
106 causes axial movement of drive coupling 108 through the
engagement of threads 110, 112 since coupling 108 and housing
146 are both prevented from rotary motion within sliding body
100 by the engagement of guide lugs 152 within slots 154.

Ratchet disk housing 146 also includes a cap 158
which is press-fit onto the distal end 160 of housing body 162
to capture a ratchet disk 164, preferably made of spring
quality stainless steel, within housing 146. Ratchet disk 164
is shown in more detail in Fig. 5B and includes a pair of
upwardly extending spring fingers 166 sized to fit within drive
grooves 90 of drive stems 88. The tips 168 of fingers 166 are
positioned to frictionally engage the drive surfaces 169 formed
at the base of drive grooves 90. Accordingly, when sliding
body 100 moves within guide sleeve 8, dose adjuster 102 moves
with the sliding body. Depending upon the relative position of
lugs 148 within slots 150, drive couplings 108 may force
ratchet disk housing 146 in a distal direction, that is in the
direction of arrow 172 in Fig. 3, or in a proximal direction,
that is in the direction of arrow 170. When housing 146 moves
in the distal direction, ratchet disks 164 force drive stems 88
in the distal direction, thus forcing pistons 96, 98 in the
distal direction causing contents 40, 42 to flow through the
common exit. It should be noted that a relatively rigid,
cupped shaped spacer 173 is used between drive stem 88 and
piston 96. This is to accommodate the larger sized piston and
minimize piston distortion.

Drive stems 88 also pass through anti-backup ratchet
plate 82 which is configured similar to ratchet disks 164.
Ratchet plate 82 prevents the movement of drive stems 88 in the
proximal direction after having been driven by ratchet disks
164 in the distal direction. The movement of sliding body 100
in distal direction 172 is halted by the abutment of distal end
156 of sliding body 100 against ledge 72 of guide sleeve 8.
The movement of sliding body 100 in proximal direction 170 is
halted by the engagement of a limit pin 174 against the
proximal end 176 of a retract limit slot 178. See Figs. 9, 9A
and 9B. In the preferred embodiment the total reciprocal
distance of movement of sliding body 100 is about 7 mm.

Figs. 9-9B also illustrate the action of post-injection
latch 84. Fig. 9A illustrates dispenser 2 after the
sliding body is at the end of the delivery stroke so it is in
the post-injection position. When this occurs, latch 84, which
is naturally biased in the direction of arrow 180, keeps
sliding body 100 in the post-injection position by the
engagement of tip 182 of latch 84 into a recess 184 formed in
slider body 100. The recess 184 is configured to limit-the
movement of the latch 84 to prevent excessive movement. This
helps prevent inadvertent movement of slider body 100 from the
post-injection position of Fig. 9A. When it is desired to move
slider body 100 in the proximal direction 170, the user presses
on latch 84 so as to pivot the latch in the direction opposite
of arrow 180 against the normal bias of the latch to move tip
182 out of recess 184 as shown in Fig. 9B. The dispenser 2 is
configured to facilitate the retraction of the slider body 100,
by, e.g., the positioning of the post-injection latch 84 and
providing retraction tabs 183, 185. Preferably, retraction tab
185 is formed as the head of the release switch 236, described
more fully below. The tabs 183, 185 are positioned on the
exterior surface of the sliding body 100 near the proximal edge
thereof. In one preferred retraction procedure the user grasps
the dispenser 2 such that, e.g., the left hand is positioned to
hold down the post-injection latch 84 in its released position
with the dispenser 2 in a substantially horizontal position and
with the status window 208 (described more fully below) upward
so as to be visible. The user than grasps the tabs 183, 185
with the right hand and pulls the slider body 100 proximally
toward the retracted position until full retraction is
indicated in the status window 208, as described below. By
providing the described position of the post-injection latch 84
and tabs 183, 185, the user is encouraged to perform retraction
in a manner which will permit the user to view the window 208
and will avoid direct compression on the slider body 100,
instead, directing pressure to the tabs 183, 185.

It is useful to provide the user with reliable and
unequivocal indication that the dispenser 2 has been fully
retracted and is in condition for administering an injection.
In the depicted embodiment, this is achieved by providing
indicia and/or flags which are positioned for viewing through a
window 208 in response to the configuration and condition of
the dispenser 2. It is particularly desired to avoid any
indication of retraction until substantially full retraction
has been achieved. In the depicted embodiment, dispenser 2
includes a status window flag 186, shown best in Figs. 2 and
10, pivotally mounted within a recessed region 188 of sliding
body 100 to pivot about a pivot point 190. Flag 186 is
bistable so that it remains in one of the two positions
illustrated in Fig. 10. This is achieved using an S-shaped,
over-center spring 192 having one end positioned in a cutout
194 formed in flag 186 adjacent pivot point 190 and another end
positioned in a receptacle 196 formed in sliding body 100.
Spring 192 is deflected between the solid line and dashed line
positions of Fig. 10 through the engagement of a pair of trip
pins 198 extending from a spring trip plate 200 carried by
guide sleeve 8. Trip plate 200 is secured by guide sleeve 8 by
the engagement of a pair of pins 202 which securely engage
holes 204 formed in guide sleeve 8. Pins 198 pass through an
opening 206 formed in guide sleeve 8. Trip pins 198 are
positioned to lie on either side of spring 192. It would be
possible to use projections (not shown) extending from the
edges of opening 206 in place of the trip pins 198. When
sliding body 100 is moved to the post-injection position of
Fig. 9A, flag 186 is moved from the dashed line position to the
solid line position of Fig. 10. Note, however, that this
occurs only during the very end of travel of sliding body, for
example, during the last 5 percent, preferably during the last
3 percent, more preferably the last one percent, of movement of
the sliding body so that the user is assured that display of
the flag 186 is a reliable indication of full retraction.
Until the time substantially full retraction, flag 186 remains
in the dashed line position of Fig. 10.

Guide sleeve 8 has an offset status window 208
covered by a lens 210. Window 208 allows the user to view the
position of flag 186. That is, when flag 186 is in the solid
line position of Fig. 10 at the end of a delivery stroke,
window 208 overlies a panel 212 formed in sliding body 100. As
indicated in Fig. 10, panel 212 typically includes indicia 214,
216 which provide status information to the user. That is,
when sliding body 100 is in the retracted position, window 208
overlies indicium 216. As sliding body 100 is moved distally,
window 208 begins to pass over indicium 216 and onto indicium
214. However, because of the bistable nature of flag 186, the
indicium 218, indicates that it is safe to perform the
injection is seen through window 208 in the fully retracted
position.

As the user pulls sliding body 100 away from guide
sleeve 8, that is in proximal direction 170, status window 208
moves from overlying indicium 214 to overlying indicium 216.
Only after sliding body 100 is in its fully retracted position
will trip pins 198 contact spring 192 thus forcing the spring
in such a way to cause status window flag 186 to move from its
solid line to its dashed line position of Fig. 10. This also
occurs during the last few percent of travel of sliding body
100. Only after the status flag 186 has been tripped will the
indicium 218 be visible to the user. Preferably, indicium 218
is green while indicia 214, 216 are different colors from
indicium 218 to quickly alert the user as to the status of
pharmaceutical dispenser 2.

The display of the various indicia and the status
flag is, useful in assuring the user that the sliding body 100
has been fully retracted and the dispenser 2 is in condition
for performing an injection. The indicia and status flag also
provide additional advantages. As described more fully below,
the status flag is useful in alerting the user that there is
not sufficient pharmaceutical in one (or both) of the
cartridges 32, 34 to deliver the dosage currently selected by
the user, as described more fully below. Once a user has
learned from the indicia and status flag that insufficient
pharmaceutical remains, the indicia and status flag can also be
used to provide a clear indication of how large a dosage can
still be delivered with the remaining pharmaceutical, as
described below. The indicia and status flag are also useful
in assisting the user to avoid waste of pharmaceutical. In one
embodiment, this achieved by instructing the user to perform
dose adjustment while the dispenser 2 is in the post-injection
configuration (i.e., to avoid adjustment while the dispenser 2
is in the retracted position). If the user attempts to
increase dosage after the retraction operation, there will be
no undesirable effects and the apparatus will operate as
intended. However, if the user attempts to decrease dosage
after moving the sliding body to the fully retracted position,
pharmaceutical will be expelled through the needle, causing
waste. Therefore, by providing a clear indication of whether
the dispenser 2 is in the retracted configuration, the user is
assisted in avoiding a dosage change while the dispenser 2 is
in the retracted position. A further aspect of the status flag
186 is the auditory "click" signal it produces when moving from
one configuration to the other. This auditory signal is
particularly useful for users with visual impairment. Thus, by
providing an auditory "click" signal the above-described
benefits of the indicia and status flag can be enjoyed by
visually impaired users as well.

Lugs 152 are slidably positioned in slots 154 of
slider body 100. As slider body 100 is translated forwardly
(during an injection stroke), the surfaces of slider body 100
that define the base of slots 154 contact the bottom portions
of lugs 152 and drive the lugs 152 and, thus, the ratchet disk
housings 146 forwardly. Since stems 88 are coupled to ratchet
disk housings 146 via ratchet discs 164, stems 88 and lugs 152
are driven forwardly the same distance. Once slider body 100
is in its post-injection position, as illustrated in Fig. 9A,
the dose for subsequent injections can be adjusted.
Specifically, dose screws 106 can be rotated to adjust the
position of lugs 148 in slot 150 through the cooperation of
threads 110 and 112. Although adjustment screw 106 can rotate
relative to slider body 100, screws 106 cannot translate
relative to the slider body. Accordingly, the position of lugs
148 in slots 150 determine the distance that ratchet disk
housings 146 travel with sliding body 100 during retraction.
For example, if dose screws 106 are rotated to position lugs
148 midway up slots 150, when slider body 100 is retracted,
lugs 148 must move a distance corresponding to half the length
of slots 150 before causing ratchet disk housing 146 to
retract. In this way, the dose is set.

Referring to Fig. 2, dose adjustment screws 106 have
four axially extending grooves placed on equal quadrants of
the screws. A pair of detent clips 234 are mounted within
sliding body 100. Detent clips 234 engage grooves 232 as
screws 106 are rotated to provide the user with both an tactile
and an audible indication of the dose being chosen. The
tactile and audible indications are particularly useful for
vision-impaired users.

Housing body 162 of ratchet disk housing 146 has an
inwardly extending projection 235, see Fig. 2, which rides
along the end of dose grooves 92 formed in drive stems 88.
When the contents 40, 42 of cartridges 32, 34 is insufficient
to accommodate the selected dose, projection 235 will contact
the end 222 of groove 92 to prevent any further proximal
movement of sliding body 100. The user will know the contents
of a cartridge is insufficient for the selected dose since the
indicator flag will not be visible through the window 208. The
user can, then, adjust dose knobs 114 to reduce the dose until
sliding body 100 is in the fully retracted position. This
will be indicated by movement of the indicator flag to align
with the window 208. The user can then determine the available
contents by viewing the position of dose indicator 132 after
flag 186 has moved to the dashed line position of Fig. 10.
Even after one cartridge is entirely depleted, pharmaceuticals
can be dispensed from the non-depleted cartridge by selecting a
"zero" dose for the depleted cartridge.

When it is decided to replace one or more of
cartridges 32, 34, the user places sliding body 100 in the
post-injection position of Fig. 9 shifts the cartridge release
switch 236, and then, rotates dose knobs 114. This causes a
single release thread, see Fig. 8, 224 formed on knob core 116
to engage an internal thread 226, see Fig. 7A, formed at the
proximal end of sliding body 100 to advance. Release forks 228
(Fig. 5), in the distal direction 172 forcing the tapered tips
230 against fingers 166 of ratchet disks 164. This axial
movement of release forks 228 causes housing 146 to move in the
distal direction so that finger engaging taper tips 232
extending from cap 158 engage fingers 166 of anti-backup
ratchet plate 82. Doing so causes fingers 166 to dilate thus
releasing their grip on drive stem 88. The user can then
remove manifold assembly 10 using release buttons 48, 50 to
expose cartridges 32, 34. The cartridges can then be removed
exposing drive stems 88. The drive stems can then be forced in
the proximal direction, new cartridges can be mounted within
receiving bores 28, 30 and a fresh manifold assembly mounted
onto cartridge housing 6. In one embodiment, the new cartridges
can be used to force the drive stems 88 in the proximal
direction. In particular, by inserting new cartridges in the
receiving boards 28, 30, and pushing the new cartridges down,
either manually or by replacing the manifold 16, the pistons
96, 98 will engage the tops of the stems 88 and insertion of
the cartridges will thus force the stems 88 proximally.
Excessive movement of the stems 88 is avoided by contact of the
proximal surface of the stems 88 with ledges 320 formed on the
forks 228.

The fingers of both the ratchet plate 82 and ratchet
disks 164 are configured so that they exert sufficient pressure
against the stems 88 and are angled with respect to the stems
88 in such a manner that they can slide in a proximal direction
with respect to the stems 88 but when moved in a distal
direction will grasp the stems 88 and thus move the stems 88
along with the ratchet disks 164. In order to make sure the
fingers retain this characteristic, it is necessary to assure
that dilation of the fingers as described above is not so
excessive that the fingers become bent or plastically deformed
to the extent that, upon removal of the tapered tips 232, 230
the fingers will not relax to the desired configuration and
angle. In order to avoid excessive dilation, as best seen in
Fig. 5, housing body 162 and the coupled cap 158 are positioned
normally (i.e., other than during dilation of the ratchet plate
82) spaced a distance 312 from the underside of the ledge 76.
As described above, to dilate the fingers 166, the cap 158 is
driven upward so that the tapered tips 232 contact the fingers
166. The amount by which the tapered tips 232 can be driven
upward is limited by contact of the caps 158 with the bottom
surface of the ledge 72 so that the cap 158 cannot be driven
upward a distance greater than the spacing 312. This upper
limit on the motion of the cap 158 provides an upper limit on
the amount by which the fingers 166 of the ratchet plate 82 can
be dilated. The underside 314 of the tapered tips 232 are
tapered upward and spaced from the fingers 166 of the ratchet
disk 164 to provide a stop preventing excessive dilation of the
fingers 166 of the ratchet disk 164. Thus, the combination of
the plate 76 acting as a stop to upward movement of the cap 158
and the tapered and spaced configuration of the lower surface
314 of the tapered tips 232 prevent excessive dilation of the
fingers 166 of both the ratchet plate 82 and ratchet disks 164.

According to the depicted embodiment, the dispenser 2
is provided with a device to avoid accidental or premature
release of the stem 88 and, preferably, to also prevent
movement of the slider body 100 to the post-injection position
while the stems 88 are released. According to the depicted
embodiment, the release switch 236 projects proximally toward
the knobs 114 and contacts the distal surface of the knobs to
act as a hold-off. In particular, the bottom surface of the
switch 236, when in the normal operating position, maintains
the knobs 114 spaced a distance from the sliding body 100
sufficient to prevent engagement of the thread 224 with the
internal thread 236. In this embodiment, in order to release
the stems 88, the user grasps the head 185 of the switch 236
and pulls laterally outwardly so that the projection on the
bottom of the switch 236 is positioned away from the knobs 114.
The knobs 114 can then be moved distally a distance sufficient
to engage thread 224 with thread 226, permitting release of the
stems 88, as described above. In order to prevent movement of
the sliding body 100, the switch 236 is provided with a
periscope-shaped latch 238. When the switch 236 is pulled
upward to the release position, the periscope latch 238 engages
an opening 240 in the guide sleeve 8 (see Fig. 7), thus
coupling the guide sleeve 8 to the sliding body 110 and
preventing relative movement. After the desired movement of
the stems 88, the knobs 114 are rotated to disengage a thread
224 from the thread 226 and lowered sufficiently to permit the
release switch 236 to be pressed laterally inward, disengaging
the periscope latch 238 (to, once again, permit relative
movement of the sliding body 100 and guide sleeve 8) and
positioning the projection on the bottom of the switch 236
adjacent the distal surfaces of the knobs 114, once again
acting as a hold-off to prevent undesired release of the stems
88.

The indicia 214, 216 are useful in connection with a
cartridge replacement by providing an indication to the user
that the stems 88 have been released. When the stems are in
the released configuration, the indicium 214 will be visible
through the window 208. The user thus can refrain from
attempting to change a cartridge until such time as the
indicium 214 is visible.

Assuming pharmaceutical dispenser 2 is in the post-injection
position of Fig. 9, the user selects the dose desired
by rotating dose knobs 114. This causes dose indicator 132 to
move along slot 138. The depicted configuration of the dose
indicator system provides a number of advantages. By providing
a linear scale with a moving indicator, dose indication is
provided in a form that is intuitively legible to most users
because of its analogous relationship to devices such as a bar
graph or a speedometer or other "needle" type indicators with
which many users will be already familiar. A moving indicator
provides advantages over, e.g., the display of a number since
the user is provided with not only a numeral indicator but also
a positional indicator so that some redundancy of indication is
provided. These aspects help safeguard against a mis-dose,
particularly among visually impaired users. The dosage
indicator of this embodiment is also useful in that it provides
a type of memory since prior to adjustment it will indicate the
dosage amounts used in the most recent injection. This is
useful for persons who wish to select a dosage based on the
most recent injection. It can also be useful for persons who
followed a prescribed pattern of dosages but have difficulty
remembering whether a particular injection from the pattern has
been administered. Referring to the last previous dosage may
assist such persons in determining which injection from a
pattern of injections was last administered.

The position of dose indicator 132 is visible along
the edges of guide sleeve 8 since guide sleeve 8 is made from a
transparent material. However, the portion of guide sleeve 8
other than the rounded edges can be painted or otherwise made
opaque, it is especially useful to render opaque that portion
overlying recessed region 188 in sliding body 100 for providing
visibility and contrasting indicia. At this point, indicator
window 208 is over indicium 218 to tell the user that the
sliding body is at the end of its delivery stroke. The user
then presses on latch 84 and pulls sliding body 100 in the
proximal direction to the retracted position. Once in that
position, flag 186 trips and moves between its solid line
position to its dashed line position of Fig. 10. Until the
slider 100 reaches the retracted position, flag 186 is not
visible beneath window 208. However, once in the retracted
position, indicium 218 is visible showing the user that the
next injection can be made. After the injection flag 186
returns to the solid line position of Fig. 10 and the procedure
can be repeated.

With the exception of cartridges 32, 34, most of the
components of dispenser 2 are made of injectable thermal
plastic, such as polycarbonate. However, septum 24, diaphragm
18 and o-rings 140 are made of conventional elastomeric
materials. Ratchet disks 164, ratchet plate 82 and over-center
spring 192 are preferably made of spring quality stainless
steel. Screw 78 and 118 are made of metal as well.

Modification and variation can be made to the
disclosed embodiment without departing from the subject of the
invention as defined in the following claims.

Claims (12)

A fluid dispenser comprising:

a housing (4);

first and second variable volume containers (32, 34)
mounted to the housing and including first and second exits and first and
second movable elements by which the contents of the containers can be
forced through said respective exits as the movable elements (96, 98) are
moved within said variable volume containers;

a pair of drive stems (88) for and drivingly coupled to each of
the movable elements, each drive stem including an axially extending
drive surface (169);

a reciprocating drive assembly, movable between a post-injection
position and a retracted position, for driving the drive stems so
as to drive the movable elements within said variable volume containers in
at least a first cycle, the drive assembly including:

a one-way drive device, including one-way drive elements
(164), drivingly coupled to the drive stems (88) along the drive surfaces by
the one-way drive elements; and

a pair of dose adjusters (102) for adjusting the relative distance
the driver and stems associated therewith travel during a cycle of
the driver; characterized by

an indicator (186) coupled to said housing, movable between a
first position, while said drive assembly is in said retracted position, and a
second position in response to movement of said drive assembly substantially
fully to said post-injection position.

A dispenser, as claimed in claim 1, characterized
in that said indicator (108) comprises a status flag pivotally
mounted to the drive assembly at a pivot point (190).

A dispenser, as claimed in claim 2, characterized
by a spring (192) positioned adjacent the pivot point (190) and
oriented to bias the status flag to either of the post-injection
and retracted positions; and

a pair of spring engaging elements (198) carried
by the housing and positioned to engage and deflect the spring
(192) when the reciprocating drive assembly is moved to the post-injection and
the retracted positions.

A dispenser, as claimed in claim 2, characterized
by a status window (208) associated with the housing, the flag
being visible through the status window when the reciprocating drive assembly
is in one of the post-injection and retracted positions, the flag
being not visible through the status window when the reciprocating drive
assembly is in the other of the post-injection and retracted
positions.

The dispenser of claim 1, characterized by a post-injection
latch (84) mounted to the housing and engagable with
the reciprocating drive assembly which, in response to moving the
reciprocating drive
assembly to the post-injection position, secures the reciprocating drive
assembly in the post-injection position until a user releases
said post-injection latch.

The dispenser of claim 1, characterized by a
manifold (10) having at least a portion moveable to a first
position to define a fluid path from the first and second exits
to a common exit.

The dispenser of claim 6, characterized in that
said dose adjusters (102) include means (104, 106) for
individually adjusting the amount each of said drive stems moves
during each cycle of the reciprocating drive assembly, each individually
adjusting means including a dose control element (114) by which a
user selects said amounts of the contents of the respective
containers forced through the first and second exits.

The dispenser of claim 7, characterized in that
the manifold (10) includes a latch (48,50) movable from a first
position holding the manifold to the housing to a second position
allowing the manifold to separate from the housing.

The dispenser of claim 1, characterized in that
the drive stems (88) have a stop surface positioned to engage
said reciprocating drive assembly to prevent movement thereof when
said reciprocating drive
assembly has driven said stems a predetermined amount so that the
stroke determined by said dose adjusters (102) exceeds the
effective remaining length of said variable volume containers.

The dispenser of claim 1, characterized by means
(166, 228, 230, 232) for selectively separating at least a
portion of the housing and therewith the variable volume
containers (32,34) from the remainder of the dispenser to permit
the user to change the variable volume containers.

The dispenser of claim 1, characterized in that
the drive surface (169) of each drive stem (88) is at least
partially defined by an axially extending slot (90) formed in the
drive stem, the one-way drive elements (164) include a spring arm
(166) positioned at an acute angle to the drive surface, the
spring arm engaging the drive surface, and further characterized
by means for selectively releasing the one-way drive elements
(164) from each drive stem (88), the selectively releasing means
including a releasing member (158, 228) mounted coaxially within
the reciprocating driver and adapted to selectively engage the
spring arm (166) so to deflect said spring arm away from the
drive surface.

The dispenser of claim 1, characterized by means
(84) for sensing when said drive stems (8) have moved a
predetermined amount and for preventing movement of said
reciprocating drive
assembly to said retracted position in response to said sensing,
said predetermined amount being controlled by movement of said
dose adjusters (102).